Splitfires, Spark Plugs, Fuel Economy ..

[Wacky Dee]

I have a '98 R34 GTT with 70k and when I had my spark plugs changed a few months ago (heatrange 7, coppers) and gapped to 0.8mm (stock coils) the car was misfiring BADLY when idle and up to 3000rpm .. it was like a constant popcorn sound and shuddering.

So the tuner changed the gap to 1mm and it fixed the misfiring for the most part. I can still hear/feel the occasional misfire/shudder when idle and I think it's getting worse when switching gears etc so I am seriously considering getting Splitfires (only $620 delivered from ebay)

I also get very bad fuel economy of 16-17l/100km around town with occasional squirts but mostly very timid driving. The tuner checked the o2 sensor codes and says it's working. My plans are to get a brand new o2 sensor, splitfires, 1.1 gap heatrange 7 plugs and to get the stock injectors cleaned.

On a slightly related note, I have developed a small vaccum leak since I have got the car. The tuner looked it over and reckons it's somewhere "after the butterfly and it would cost up to $800 in labour" to find where it is and to fix.

How does a small vaccum leak affect car's performance and fuel economy? When I first got the car my EBC (greddy) was showing -98 or -99 vaccum when idle but now it's in the -80's or higher and only once the engine warms up completely it goes up to -92 or so, so there's definately a vaccum leak somewhere.

Anyway my plan is to get Splitfires, new spark plugs with the default 1.1 gap (heat range 7) a new o2 sensor, get the injectors cleaned, put a FMIC at the front (the stealth one from JJ) and then get the ecu returned by Toshi.

Can anyone recommend which type/brand of spark plugs to use ? I'd rather get something recommended by other skyline owners than whatever my tuner has in stock. I want coppers heat range 7 with 1.1 gap.

Also most importantly, where can I get my stock injectors cleaned properly ? Is there anyone who does this in Sydney? Cheers

[The Dan]

You could start by getting the correct plug.

They have a heat range of 5 as standard. Why in the world would you put a 7 in...unless you are making 500hp.

Check to make sure your fuel filter is not blocked and make sure the pump is still well alive

[Wacky Dee]

fuel filter was changed at most recent service ..not sure about pump. Oh and regarding heat range, not so sure about 5 being the stock one. Anyway, I'm going with 7 after getting a talking to from my tuner (Yavuz at Unigroup) about idiots that use heat range 5 and 6 in skylines

[cosmic starz]

I have a '98 R34 GTT with 70k and when I had my spark plugs changed a few months ago (heatrange 7, coppers) and gapped to 0.8mm (stock coils) the car was misfiring BADLY when idle and up to 3000rpm .. it was like a constant popcorn sound and shuddering.

So the tuner changed the gap to 1mm and it fixed the misfiring for the most part. I can still hear/feel the occasional misfire/shudder when idle and I think it's getting worse when switching gears etc so I am seriously considering getting Splitfires (only $620 delivered from ebay)

I also get very bad fuel economy of 16-17l/100km around town with occasional squirts but mostly very timid driving. The tuner checked the o2 sensor codes and says it's working. My plans are to get a brand new o2 sensor, splitfires, 1.1 gap heatrange 7 plugs and to get the stock injectors cleaned.

On a slightly related note, I have developed a small vaccum leak since I have got the car. The tuner looked it over and reckons it's somewhere "after the butterfly and it would cost up to $800 in labour" to find where it is and to fix.

How does a small vaccum leak affect car's performance and fuel economy? When I first got the car my EBC (greddy) was showing -98 or -99 vaccum when idle but now it's in the -80's or higher and only once the engine warms up completely it goes up to -92 or so, so there's definately a vaccum leak somewhere.

Anyway my plan is to get Splitfires, new spark plugs with the default 1.1 gap (heat range 7) a new o2 sensor, get the injectors cleaned, put a FMIC at the front (the stealth one from JJ) and then get the ecu returned by Toshi.

Can anyone recommend which type/brand of spark plugs to use ? I'd rather get something recommended by other skyline owners than whatever my tuner has in stock. I want coppers heat range 7 with 1.1 gap.

Also most importantly, where can I get my stock injectors cleaned properly ? Is there anyone who does this in Sydney? Cheers

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must rate closely as one of the most illogical posts so far for 2009 - your proposed repairs appear total guesswork - and why would you need to replace the spark plugs and the 02 sensor - the plugs are virtually new according to you and you have been advised the 02 sensor is Ok by your "tuner" - lol

if you don't trust your tuner why not get a new tuner and have a new expert opinion before starting out on a raft of repairs - maybe thats too logical?

and " most importantly" the injectors need cleaning at 70k ? I doubt it...........but hey if it makes you feel good ..........

in fact, why would'nt you just fix the vac leak you are positive exists and then see if the problems are still there = but maybe thats too logical also - lol

fixing vac leaks and misfires is not rocket science = anybody with some elementary mech skills and just some basic tools should be able to master it - so why not do some research, get some hands on experience, and dump your tuner and have a go yourself, and save yourself the $800 and other costs, including the unnecesary ones mentioned above?

[The Dan]

I'm going with 7 after getting a talking to from my tuner (Yavuz at Unigroup) about idiots that use heat range 5 and 6 in skylines

Wow, Nissan are idiots now.

Yavuz needs to wise up. The listed plug is a 5 but most people go to a 6 when they wind up the power slightly. 7's are for when you are making 250-350kw at the wheels.

[Wacky Dee]

mr gray, I've been driving the skyline for a year now and not getting more than 300km/50l - that's close to a thousand bucks in wasted fuel compared to most other similar skylines so THAT's why I'm going on this little crusade to once and for all fix this issue.

o2 sensor showed up as OK but it's a 11yo car and it since new ones are dirt cheap, why not give it a try? Same thing with the injectors..what's the harm in getting them cleaned and replacing the seals when it costs < $150 ? The odo may say 70k but who really knows what the real number is since it's an import.

As for vaccum leaks, you didn't even attempt to answer my question (which was how it might affect performance and/or fuel economy) but instead used it as another excuse to continue your stupid attack. Maybe I don't have the necessary tools, time and experience to f**k around with engine repairs myself, did you ever think of that ?

I think your whole response can be regarded as one of the ugliest, most useless responses of 2009 so far - you've done nothing but aggravate me with your high and mightyness without answering a single question. Well done.

[Wacky Dee]

Wow, Nissan are idiots now.

Yavuz needs to wise up. The listed plug is a 5 but most people go to a 6 when they wind up the power slightly. 7's are for when you are making 250-350kw at the wheels.

It's been a while now since I had this chat with him about spark plug heat range (at least 6 months) so I'm not gonna quote him for fear of misquoting ... erm if that makes sense. But if my memory serves me correctly, he presented his argument well and it made perfect sense at the time. Yes he could be wrong rah rah rah but I trust his advice, so let's just leave it at that and leave the spark plug heat range out of the discussion

[blind_elk]

The spark plug heat range needs to be in the discussion. If you have the wrong heat range, then the spark plug will not perform to its optimum. And if it doesn't perform to optimum, you get crap fuel economy.

Leave the f****n O2 sensor out of the equation. You are driving mostly city (ie stop / start), so the ECU will be generally ignoring anything the O2 sensor tells it (read any of the 1,278,943 other threads in here regarding where / when / how the O2 sensor works).

[Wacky Dee]

All I remember was that when I kept insisting on getting a 'heat range 6' plug because that's what everyone on SAU recommends I was given a lecture .. in a nice way I remember Yavuz saying, have a look at the tip of the spark plugs when we take them out next time and if they're fouled and not perfectly clean I'll eat my hat - or something to that effect.

Anyway, I was getting the same shit economy even before the spark plug change and I'm pretty sure the previous plugs were 6's so they're unlikely to be the cause of the bad fuel economy. I've read quite a few threads with people who get similarly crap economy as me who've changed the o2 sensor and nothing improved. So I might just start with the injector cleaning/replacing seals to rule that out as it's quick and cheap (found a mobile injector guy)

[joeyjoejoejuniorshabadoo]

i've been on bcp7res 0.8 gap for 150, 180, 270 and 310rwkw... never had an inkling of a problem

[Wacky Dee]

yeah i just did a quick search again on heat range discussions ..and a few people (incl. obviously my tuner) say to get the 7's, one of the mentioned pre-reqs for colder plugs is if you're running more than stock boost which I am (12psi vs stock which is 8psi I believe) otherwise to stick to 6s

[charlie22]

Why even ask for opinions if you have your mind made up on what your going to do anyway?

You have been given advice only to label them "useless" and "ugly".

Way to go.

[Wacky Dee]

who says I made my mind up ? I didn't ask anything about spark plug heat ranges. I may have mentioned them but I didn't ask "which heat range plugs should I use" BECAUSE I've been through that before and have settled with 7s which work fine. If you do a friggin search on SAU you'll find various opinions but MOST of the people in the know keep repeating what my mechanic said ie. heat range 7 is the right heat range for a modified skyline running more boost than stock with other mods.

And READ mr gray's post, it's all just smart arse remarks but not a single piece of useful advice or explanation as to why I should make fixing a minor vac leak my priority when all the other things are mentioned OVER AND OVER in various threads as possible causes of misfiring and bad fuel consumption.

God I f**king hate this place sometimes. When I know something that's being asked by someone else I try and help by answering the question, if I don't know the answer I read what other people have to say and try to learn something. Why do I get smartarses and f**kwits in my threads everytime? f**k OFF IF YOU HAVE NOTHING USEFUL TO ADD OR IF YOU JUST WANT TO PUT SOMEONE ELSE DOWN.

[nuffsaid]

I would have to agree with Delta Force there

I think KV2R34GT's post could have been less sarcastic, sometimes people on the forums just want honest help and dont know. Give us a break, sometimes all we need is guidance or confirmation.

I'd check the vacuum leak if there is one as they are known to produce poor fuel economy problems (dont ask me why but thats what i have read)

Supposedly 02 sensors need to be replaced every 60000kms or soemthing like that. So it is probably time to change it anyways, it may be working okay sometimes, and soemtimes the readings may be off a little. Get a genuine nissan one off a trader named Kudos here. As far as I know, there arent any direct replacements for the R34 GTT other than the OEM one, worth the $170 i think.

[ducki]

I replaced my o2 with an EL falcons o2 sensor awhile ago... apparently its a direct fit but you gotta change the plug... use the plug from your old o2 sensor.

[nuffsaid]

I did the same, but used a Ford plug instead and wired that in (Ford plug uses copper wire which is easier to solder than the stainless steel type wire in the R34 plug)

Ford O2 sensor is $65 roughly, plug you can find from a ford wrecker. supposedly the specs are the same but no one has ever really confirmed.

But for the trouble, I;d just go with buying a genuine nissan one.

[Wacky Dee]

The listed plug is a 5 but most people go to a 6 when they wind up the power slightly. 7's are for when you are making 250-350kw at the wheels.

I'll get the mechanic to take out the spark plugs when I get the injectors cleaned and inspect the plugs to see if they're fouled. I have no problems replacing them with 6s if indeed there appears to be an issue as they're only $20 for 6 of them anyway. Been doing a bit more researching and it seems a lot of people run 6s without issues, even though others swear you shouldn't have anything less than 7s. I guess wait and see what comes out

Thanks nuffsaid, I agree. Last thing I need when there's so much conflicting info out there is a smartarse just wasting my time NOT telling me how to fix something but saying crap like "oh yeah anyone can fix that, its not rocketscience" and shit like that. Just look at how many people have bad fuel economy issues and have to spend countless hours and try a hundred different things to get a result.

In regards to the vaccum leak, I'll have a speak to Yavuz soon. My last impression was that it could be a VERY costly excercise which is why I thought bugger it esp. when someone told me the average skyline has less vaccum than mine does now with this leak. I think I remember someone saying their EBC shows -60 when idle ... mine is roughly -90 when warmed up.

[geraus]

im doing 233kws at the moment with BCPR7ES 0.8mm and there working fine! but when i had BCPR6ES 1.1 gapped with my same tune it was missing sometimes...!

[Wacky Dee]

stock coils or splitfires?

[blind_elk]

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and " most importantly" the injectors need cleaning at 70k ? I doubt it...........but hey if it makes you feel good ..........

Got an email from Steve at Wolf last night, extolling the virtues of having clean injectors. He highlighted the fact that dirty injectors with poor spray patterns can have an adverse effect on fuel economy.

So cleaning the injectors will, more than likely, make you feel good. Who knows what crap has snuck past the fuel filter and embedded itself on the needle of the injector.